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Help. Brake probs.
Posted: Wed Mar 02, 2016 2:28 pm
by zephyrgary
Having probs getting a decent pedal after a brake job. My mechanic ( an old timer but not necessarily a Brit car guy) replaced every component in the system. Master, all 6 slaves and all three hoses with the good stuff from Powertrack UK. However the pedal is low and I have hit floorboard on occasion. The master was bench bled and is working fine. He says it is something to do with the floating slave arrangement on the rear which means nothing to me. I have been told to drive it a bit and then re-adjust the rears, but does anyone here have any advice or prior experience? Thanks guys.
Gary
Posted: Wed Mar 02, 2016 6:33 pm
by Bob_S
Hi Gary,
If the brakes are't adjusted correctly, the brake shoes and wheel cylinders have to move along way before contacting the drums. The pedal could go to the floor or close to the floor because the volume of the master cylinder isn't enough in one stroke to over come the additional travel of the wheel cylinders. It can also make it hard to manually bleed all the air out of the system. I have experienced this on one of my cars, non English Ford.
I would readjust the brakes, try bleeding the brakes again and see if it improves.
Posted: Thu Mar 03, 2016 8:39 am
by enfoprefect
If you can bring the pedal up by pumping, that's an almost sure sign of low adjustment. If it's air in the lines then pumping probably won't help.
Posted: Thu Mar 03, 2016 10:57 am
by JAN
I'm not sure what car you have but many 50s - 60s Fords were a pig to bleed. The problem is actually the orientation of the bleed valves, which on these cars were at the lowest point. Air rises in a liquid. and the effect is that each time the pedal is released to allow the master cylinder to recuperate, the air that had been forced down towards the bleed valve moves back upwards again. It never reaches the valve, so stays in the system.
The methods people use are:
1) use a power bleeder to pressurise the reservoir
2) use a vacuum bleeder attached to the valve
3) my own system, which I've never known to fail but needs three people and a lot of fluid (but less than repeated failed attempts!). Open each valve in turn ONE full turn. Start at the rear, side away from the master cylinder. Give the pedal 20 pumps hard and fast, with someone maintaining the reservoir level. This gets the fluid moving quickly and does not allow the air sufficient time to work its way back upwards. Next do the other side rear, five to seven pumps should do. Then the front away from the master cylinder, about 15 pumps, then five on the other side front, Don't bother watching for air bubbles, just get the fluid moving fast and it will take the air with it. And don't close the valve between pumps.
Posted: Thu Mar 03, 2016 6:00 pm
by zephyrgary
Thanks guys. I should have said 1959 MK2 drum brake Zephyr. I will have a go at another adjustment and a vacuum bleed to see it it helps.
BTW, a trick I learned on my MK1 zephyr was this. They are notoriously hard to bleed properly so you bleed it to where you have a halfway decent pedal then you chock down the pedal with a piece of wood. Next day all the air is gone and the pedal is firm. Worked twice for me but not on this one. Thanks again.